/** 
 * @file llxorcipher.h
 *
 * $LicenseInfo:firstyear=2003&license=viewergpl$
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 * Copyright (c) 2003-2009, Linden Research, Inc.
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 * Second Life Viewer Source Code
 * The source code in this file ("Source Code") is provided by Linden Lab
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 * There are special exceptions to the terms and conditions of the GPL as
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 */

#ifndef LLXORCIPHER_H
#define LLXORCIPHER_H

#include "llcipher.h"

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// Class LLXORCipher
//
// Implementation of LLCipher which encrypts using a XOR pad.
//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

class LLXORCipher : public LLCipher
{
public:
	LLXORCipher(const U8* pad, U32 pad_len);
	LLXORCipher(const LLXORCipher& cipher);
	virtual ~LLXORCipher();
	LLXORCipher& operator=(const LLXORCipher& cipher);

	// Cipher functions
	/*virtual*/ U32 encrypt(const U8* src, U32 src_len, U8* dst, U32 dst_len);
	/*virtual*/ U32 decrypt(const U8* src, U32 src_len, U8* dst, U32 dst_len);
	/*virtual*/ U32 requiredEncryptionSpace(U32 src_len) const;

	// special syntactic-sugar since xor can be performed in place.
	BOOL encrypt(U8* buf, U32 len) { return encrypt((const U8*)buf, len, buf, len); }
	BOOL decrypt(U8* buf, U32 len) { return decrypt((const U8*)buf, len, buf, len); }

#ifdef _DEBUG
	// This function runs tests to make sure the crc is
	// working. Returns TRUE if it is.
	static BOOL testHarness();
#endif

protected:
	void init(const U8* pad, U32 pad_len);
	U8* mPad;
	U8* mHead;
	U32 mPadLen;
};

#endif
